Hypocalcemia Definition

Hypocalcemia is a type electrolyte imbalance in which the calcium levels in the blood are lower than the normal values [1]. The normal serum calcium levels range from 8.5 mg/dL to 10.5 mg/dL [2].

Calcium Homeostasis

Calcium is one of the most numerous electrolytes present in the body. This electrolyte performs vital roles in cellular functions, neurotransmission, musculoskeletal functions, and blood homeostasis [3].

Its regulation is maintained by the parathyroid hormone (PTH), calcitonin and vitamin D. It is also affected by other electrolytes such as magnesium and phosphorus.

Normally, the food ingested that contains calcium undergoes absorption at the intestines. Then, later on, it is excreted in the urine. Even if the body consumes calcium-rich foods, the calcium levels are still regulated.

1. Parathyroid Hormone (PTH)

This stimulates the bone reabsorption of calcium.

Responsible for mediating the absorption of calcium in the intestines.

2. Vitamin D

Plays a role in controlling the release of PTH

Facilitates the stimulation of bone reabsorption by the PTH

Triggers the absorption of calcium in the intestines

3. Calcitonin

Maintains balance by lowering the calcium levels by addressing losses at the bone, GI, and renal sites.[4]

Picture 1: Calcium MetabolismSource: en.wikipedia.org

Hypocalcemia Causes

When the body is in the hypoglycemic condition, 40% of the serum plasma is bound or attached to albumin. The remaining serum calcium fractions are unbound or free. These are referred to as ionised calcium. The ionised percentage of calcium is important because these are physiologically active [5].

The level of calcium circulating in the body can be influenced by different factors and can be impaired by imbalances in the absorption, distribution, and excretion of calcium [3].

The following are the common causes of hypocalcemia:

Parathyroid Hormone Imbalances

1. Absent/Low Levels of Parathyroid Hormone (Hypoparathyroidism)

Parathyroid destruction: This may be caused by factors such as radiotherapy, metastases, systemic diseases, or surgery.

Hypocalcemia in Newborns

In newborns, hypocalcemia is termed as Neonatal Hypocalcemia. It is divided into two, according to its onset. These are:

Early Hypocalcemia: This occurs within the first three days of the newborn’s life.

Late Hypocalcemia: The onset is usually from fifth to tenth days of life. This occurs most commonly following several days of giving formula feedings to the baby. This is associated with some formulas which contain high levels of phosphate that causes the lowering of the serum calcium levels.[11]

Neonatal Hypocalcemia Causes

Prematurity (babies who were born early) and low birth weight

Diabetic Mother

Dystocia (difficult birth)

Episodes of hypoxia (low oxygenation level)

Stress due to severe illness

Infection

Certain medications[11, 12]

Neonatal Hypocalcemia Symptoms

In some newborns, the symptoms of hypocalcemia may not be noticed. However, the symptoms occurring in newborns and its onset vary. Here are some of the symptoms of hypocalcemia in newborns:

Poor feeding

Lethargy

Irritability, jitteriness

Tremors, muscle twitches

Seizure[11]

Picture 2: Calcium intake of newbornsSource: endotext.org

Hypocalcemia Treatment

The approach used in treating hypocalcemic patients is influenced by factors such as severity, cause, symptoms, and its onset. The following are the managements used in treating hypocalcemia:

Advised in hypocalcemic patients, especially those who have chronic renal failure[10, 11]

Hypocalcemia Exams and Tests

Patient Health History

Determined by the health care provider to pinpoint the underlying cause of hypocalcemia. Some questions regarding symptoms may be asked.[7]

Physical Assessment

The doctor will assess for any present symptoms manifested by the patient. The most common noted signs of hypocalcemia are:

1. Chvostek’s sign

Elicited by tapping the location of the facial nerve (Located below the zygomatic arch, just in front of the ears)

Positive Chvostek’s sign: As the tapping on the facial nerve is done, twitching of the facial areas, specifically, nose, mouth, and cheek will occur.

Picture 3: Chvostek’s signSource: quizlet.com

2. Trousseau’s sign

This occurs due to neuromuscular excitability.

To determine the presence of this, a blood pressure cuff will be needed.

The blood pressure cuff will be wrapped and pumped up until the patient’s systolic level. Then, it is kept at that pressure for several minutes.

Positive Trousseau’s sign is indicated when carpopedal spasm occurs. This is the flexion of the metacarpophalangeal joints, and wrist, adduction of fingers and thumbs, as well as extension of the interphalangeal joints.

Paresthesias located at the fingers may also be felt by the patient.[5]

Picture 4: Trousseau’s signSource: medicalmystery.org

Laboratory Work-Ups

1. Serum Ionized Calcium

Most definitive diagnostic test for hypocalcemia.

A serum calcium level below 8.5 mg/dL indicates hypocalcemia.

2. Serum Electrolytes

Includes checking of serum Phosphorus and Magnesium

3. Parathyroid Hormone Level

Classified as an anti-body-mediated radioimmunoassay.

This should be performed as soon as possible to a patient with hypocalcemia.

4. Vitamin D metabolites

In most hypocalcemic patients, vitamin D is suspected.

Measures 1,25 (OH)2 D and 25 (OH) D

Deficiency in 1,25 (OH)2 D, when combined with high PTH levels, indicates ineffectiveness of the PTH. This is common in patients with chronic renal failure and rickets.

On the other hand, lack of 25 (OH) D is suggestive of Vitamin D insufficiency caused by malabsorption, lack of its nutritional intake, and lack of sunlight exposure.